Each bank only shows you its own slice. finO$ puts all your accounts together so you see the full picture, without building a spreadsheet by hand.
Moving money from checking to savings isn't income or spending. finO$ spots it and doesn't count it twice.
Example
You thought you earned $52,500 MXN a month. With your accounts together you see it's $42,500 MXN: the other $10,000 MXN were transfers between your own accounts.